r1 = 0.2
r2 = 0.3
a1 = 0.001
a2 = 0.002

x = [100]
y = [200]
years = range(50)

for i in years[1:]:
    x.append(int(x[-1]*(1+r1-a1*y[-1])))
    y.append(int(y[-1]*(1-r2+a2*x[-1])))
print(x[:25])
print(x[25:])
print(y[:25])
print(y[25:])